App router to Django Rest Framework 2.3.5

routers.py

from django.core.exceptions import ImproperlyConfigured
from django.db.models import get_app
from django.utils.importlib import import_module

from rest_framework.routers import DefaultRouter
from rest_framework.urlpatterns import format_suffix_patterns


class App(DefaultRouter):
    """
    Extends ``DefaultRouter`` to work with django apps in order to decouple
    ``urls`` modules

    It register the ``routers`` tuples in <app>.urls module, and also prepend
    extra urls defined in ``router_patterns``

    ** Example **

    test_app.urls ::

        routers = (
            (r'url_prefix', ViewSet),
            (r'other_prefix', OtherViewSet, 'with_base_name')
        )
        router_patterns = patterns('',
            url(...)
        )

    project.urls ::

        router = App()
        router.register_app('test_app')

        urlpatters = patterns('',
            (r'^main-prefix/', router.urls)
        )

    instead of project.urls ::

        router = DefaultRouter()
        router.register(r'url_prefix', test_app.views.ViewSet)
        router.register(r'other_prefix', test_app.views.OtherViewSet,
                        'with_base_name')

        urlpatterns = patterns('',
            (r'^main-prefix/', test_app.urls.router_patterns),
            (r'^main-prefix/', router.urls)
        )
    """
    def __init__(self, *args, **kwargs):
        super(App, self).__init__(*args, **kwargs)
        self.extra_urls = []

    def register_app(self, app_name):
        get_app(app_name)  # Assert
        app_urls_module = import_module("%s.urls" % app_name)
        try:
            routers = getattr(app_urls_module, 'routers')
            router_patterns = getattr(app_urls_module, 'router_patterns',
                                      False)
            if router_patterns:
                self.extra_urls += router_patterns
            for router in routers:
                super(App, self).register(*router)
        except AttributeError:
            raise ImproperlyConfigured("You should define ``routers`` tuple "
                                       "in '%s'.urls module" % app_name)

    def get_urls(self):
        default_urls = super(App, self).get_urls()
        extra_urls = self.extra_urls
        if self.include_format_suffixes:
            extra_urls = format_suffix_patterns(extra_urls)
        return extra_urls + default_urls